The present invention relates to refrigeration systems, and in particular to improvements in refrigeration systems of the type in which water is directly evaporated to generate cold heat.
In some of refrigeration systems of such a type, as disclosed in Japanese Patent Kokoku Publication No. H05-6105, the evaporator is depressurized by the compressor, and water present in the evaporator is caused to evaporate so that a target for cooling is cooled.
Further, in some other type of refrigeration system, as disclosed in Japanese Patent Kokai Publication No. H07-43039, a water solution of ammonia is used as a refrigerant and an evaporator provided with a moisture permeable membrane is disposed. The evaporator of this refrigeration system is divided into a depressurization space and a refrigerant passageway, and a part of the refrigerant evaporates and passes through the moisture permeable membrane from the refrigerant passageway, going into the depressurization space. This generates a refrigerant which is cold heat. A target for cooling is cooled by this refrigerant in the heat exchanger, and meanwhile, refrigerant gas separated in the evaporator is compressed by the compressor. Thereafter, the refrigerant from the heat exchanger, after absorbing the compressed refrigerant gas in the absorber, is brought back again to the evaporator. Then, such an operation is repeatedly carried out.
In the above-described conventional refrigeration system (Japanese Patent Kokai Publication No. H06-257890), in order to directly evaporate water, it is necessary to drive the compressor to compress water vapor from a saturation vapor pressure at an evaporating temperature up to a saturation vapor pressure at a condensation temperature.
However, the input of the compressor is not taken into consideration at all, and generally compressors are driven by electric motor. That is, compressors are driven by electrical energy alone, therefore producing the problem that there is a limit to the improvement in efficiency.
On the other hand, the above-described refrigeration system making utilization of a water solution of ammonia or the like (as disclosed in Japanese Patent Kokai Publication No. H07-43039) also produces some problems. One problem is that the operating temperature and the operating pressure of the system are limited by the properties of the water solution such as corrosiveness. Another problem is that there is a limitation that the use of a special material is required.
Bearing in mind the above-described problems with the prior art techniques, the present invention was made. Accordingly, an object of the present invention is to generate cold heat by evaporating water at high efficiency.
In the present invention, the pressure increasing means makes use of thermal energy as its input.
More specifically, as shown in FIG. 1, the present invention discloses a refrigeration system in which water is evaporated to generate cold heat and water vapor produced is increased in pressure by pressure increasing means (50) and then discharged, and the pressure increasing means (50) is driven at least by mechanical power derived from thermal energy.
Further, the refrigeration system of the present invention may include: a cold heat generating means (40) in which water serves as a refrigerant; the water is evaporated to generate cold heat; and water vapor produced is drawn into the pressure increasing means (50); a moisture discharging means (60) for discharging water vapor increased in pressure by the pressure increasing means (50); and a prime mover (80) for generating mechanical power from thermal energy to drive the pressure increasing means (50).
Further, the refrigeration system of the present invention may further include an electric motor (52) which generates mechanical power from electrical energy to drive the pressure increasing means (50) together with the prime mover (80).
Further, in the refrigeration system of the present invention, the prime mover (80) may be a steam turbine (80).
Further, in the refrigeration system of the present invention, the steam turbine (80) may utilize an excess of water vapor.
Further, the refrigeration system of the present invention may further include a boiler (81) which utilizes waste heat to generate a supply of water vapor to the steam turbine (80).
Further, the refrigeration system of the present invention may further include: a boiler (81) which utilizes waste heat to generate a supply of water vapor to the steam turbine (80); and a superheating means which superheats water vapor generated in the boiler (81).
Further, in the refrigeration system of the present invention, the pressure of the boiler (81) may be set below atmospheric pressure.
Further, in the refrigeration system of the present invention, water vapor discharged from the steam turbine (80) is mixed with water vapor discharged from the pressure increasing means (50) and then discharged from the moisture discharging means (60).
Further, in the refrigeration system of the present invention, sensible heat produced in the pressure increasing means (50) may be collected and the collected heat is utilized to generate a supply of water vapor to the steam turbine (80) or to superheat water vapor.
Further, in the refrigeration system of the present invention, the moisture discharging means (60) may include a water vapor permeable membrane (61) allowing water vapor to pass therethrough so that water vapor can be discharged into the atmospheric air because of a difference in water vapor pressure created between partition spaces divided by the water vapor permeable membrane (61).
Further, in the refrigeration system of the present invention, the cold heat generating means (40) may include: a humidification cooler (41) which supplies water to air to be conditioned so that the air is cooled; and a dehumidifier (42) which dehumidifies the air cooled by the humidification cooler (41).
Further, in the refrigeration system of the present invention, the cold heat generating means (40) may include: a dehumidifier (42) which dehumidifies air to be conditioned; and a humidification cooler (41) which supplies water to the air dehumidified by the dehumidifier (42) so that the air is cooled.
Further, in the refrigeration system of the present invention, the dehumidifier (42) may include a water vapor permeable membrane (4b) allowing water vapor to pass therethrough so that water vapor can be removed because of a difference in water vapor pressure created between partition spaces divided by the water vapor permeable membrane (4b).
Further, in the refrigeration system of the present invention, the cold heat generating means (40) may directly spray air to be conditioned with water so that the to-be-conditioned air is cooled.
Further, in the refrigeration system of the present invention, the humidification cooler (41) may include a moisture permeable membrane allowing water vapor to pass therethrough so that water evaporates and then passes through the moisture permeable membrane to humidify and cool air.
Further, in the refrigeration system of the present invention, the cold heat generating means (40) may include an evaporation cooler (43) which supplies cold heat generated by water evaporation to air to be conditioned so that the to-be-conditioned air is cooled.
Further, in the refrigeration system of the present invention, the cold heat generating means (40) may include an evaporation cooler (43) which generates cooling water by water evaporation.
Further, in the refrigeration system of the present invention, the cold heat generating means (40) may include an evaporation cooler (43) which generates ice by water evaporation.
Further, in the refrigeration system of the present invention, the evaporation cooler (43) may cause water to undergo direct evaporation in a low pressure space.
Further, in the refrigeration system of the present invention, the evaporation cooler (43) may include a moisture permeable membrane (4f) allowing water vapor to pass therethrough so that water evaporates and passes through the moisture permeable membrane (4f) to a low pressure space.
Further, the refrigeration system of the present invention may further include a humidity controlling means (73) which controls the humidity of outside air whose moisture content is discharged by the moisture discharging means (60).
Further, in the refrigeration system of the present invention, the humidity controlling means (73) may include a heat exchanger (7b) which increases the temperature of outside air by utilizing waste heat.
That is, in the boiler (81) of the present invention, high temperature water vapor is generated by heating water. This high temperature water vapor is supplied to the steam turbine (80). The steam turbine (80) which is a prime mover generates rotational power by expansion of the water vapor.
The pressure increasing means (50) is driven by the rotational power generated by the steam turbine (80). The pressure increasing means (50) may be driven both by output from the steam turbine (80) and by output from the electric motor (52).
On the other hand, in the cold heat generating means (40), cold heat is generated by evaporating water for the cooling of air. More specifically, for example, indoor air flows into the humidification cooler (41) and, at the same time, water is supplied to the humidification cooler (41), so that the air is sprayed with the water. The air is cooled when the water undergoes evaporation and changes to saturated air.
This saturated air flows in a dehumidification space of the dehumidifier (42). Since the pressure increasing means (50) is being driven, a low pressure space is formed through the water vapor permeable membrane (4b) in the dehumidifier (42). The water vapor pressure of this low pressure space is lower than the water vapor pressure of the dehumidification space on the other side, so that water vapor contained in the saturated air passes through the water vapor permeable membrane (4b) and migrates to the low pressure space. As a result, the saturated air is dehumidified, thereby generating temperature- and humidity-conditioned air. This conditioned air is supplied indoors for providing cooling.
Meanwhile, water vapor, which has been separated in the moisture discharging device (60), is drawn into the pressure increasing means (50) where the water vapor is compressed to an increased pressure. This increased-pressure water vapor flows in the moisture discharging means (60). At that time, the water vapor is mixed with water vapor discharged from the steam turbine (80) and flows into the moisture discharging means (60).
For example, outside air flows into the moisture discharging means (60). Since the water vapor pressure of a high pressure space of the moisture discharging device (60) is higher than the water vapor pressure of a moisture discharge space on the other side thereof, water vapor passes through the water vapor permeable membrane (4b) and migrates into the moisture discharge space. As a result, both water vapor from the pressure increasing means (50) and water vapor from the steam turbine (80) are discharged into the outside air. This water vapor cycle is repeatedly carried out so that the room is cooled. The steam turbine (80) may expel water vapor into the atmospheric air.
Further, in another invention, outside air whose moisture content has been discharged by the moisture discharging means (60) is dehumidified in the humidity controlling means (73). Especially, outside air whose moisture content has been discharged is heated in the heat exchanger (7b), and a solid or liquid adsorbent of the humidity controlling means (73) is regenerated by the heated outside air. At that time, as the heat that is supplied to the heat exchanger (7b), a variety of heats such as fuel cell waste heat may be utilized.
Furthermore, in the cold heat generating means (40), air may be dehumidified in the dehumidifier (42) and thereafter cooled by being sprayed with water in the humidification cooler (41). Further, the cold heat generating means (40) may generate, in addition to cooling air, cooling water or ice.
Additionally, the humidification cooler (41) and the evaporation cooler (43) may be constructed so that water is evaporated and passes through the moisture permeable membrane (4f).
Further, an excess of water vapor produced in a factory or the like may serve as water vapor that is supplied to the steam turbine (80). Furthermore, the boiler (81) may utilize various types of waste heats to generate high temperature water vapor.
Furthermore, various types of waste heats may be utilized for the generation of water vapor (for latent heat) in the boiler (81) and the following superheating of water vapor (for sensible heat) may be carried out by gas combustion and an electric heater, or by a superheating means such as pyrogenetic reaction.
Further, sensible heat of high temperature water vapor discharged from the pressure increasing means (50) may be collected and utilized for the generation of water vapor that is supplied to the steam turbine (80) or for the superheating of water vapor.
In accordance with the present invention, thermal energy is utilized to actuate the pressure increasing means (50). This makes it possible to make utilization of various types of energies to drive the pressure increasing means (50), thereby improving energy efficiency.
Further, cold heat is obtained by evaporation latent heat of water, thereby making it possible to perform air conditioning or the like without causing environmental problems.
Furthermore, if an excess of water vapor produced in a factory is supplied to the steam turbine (80), this improves efficiency to a further extent.
Further, if the boiler (81) makes utilization of a variety of waste heats to generate high temperature water vapor, this makes it possible to utilize fuel cell waste heat, and as a result it is possible to further improve efficiency.
Further, if various types of waste heats can be utilized for the generation of high temperature water vapor in the boiler (81) and the following superheating of water vapor is carried out by another superheating means, this makes it possible to achieve the improvement in COP because the amount of heat for sensible heat is small.
Further, if water vapor in the steam turbine (80) is discharged into the atmospheric air, this makes it possible to simplify the arrangement of the whole system.
Furthermore, if sensible heat of high temperature water vapor discharged out of the pressure increasing means (50) is collected and utilized to generate water vapor that is supplied to the steam turbine (80) or to superheat water vapor, this heat collection makes it possible to further improve efficiency.
Further, if water vapor from the pressure increasing means (50) is discharged through the water vapor permeable membrane (4b) of the moisture discharging means (60), then the pressure increasing means (50) is just required to increase the pressure of discharging water vapor above the water vapor pressure of outside air, and the amount of increasing pressure can be made smaller in comparison with cases where water is caused to condense. As a result, it becomes possible to reduce the input of the pressure increasing means (50). At the same time, it is possible to increase the expansion ratio of the steam turbine (80), thereby making it possible to improve the output of the steam turbine (80).
Furthermore, if the moisture discharging means (60) discharges water vapor from the steam turbine (80) through the water vapor permeable membrane (4b), this makes it possible to increase the expansion ratio, and the pressure increasing means (50) can be driven with a less amount of water vapor.
Further, if the cold heat generating means (40) is made up of the humidification cooler (41) and the dehumidifier (42), this makes it possible to separately control the temperature and the humidity of air to be conditioned, and it becomes possible to generate accurately conditioned air.
Furthermore, if the dehumidifier (42) includes the water vapor permeable membrane (4b), it is only required that the suction pressure of the pressure increasing means (50) be made lower than the water vapor pressure of air. This makes it possible to reduce the input of the pressure increasing means (50).
Further, if the humidification cooler (41) includes a moisture permeable membrane, this makes it possible to prevent the occurrence of scale or the like.
Furthermore, if the cold heat generating means (40) supplies cold heat to air to cool it, this prevents the air from being mixed with water, and this arrangement can be applied also in cases where strict moisture control is essential.
Further, if the cold heat generating means (40) generates cooling water, this makes it possible to construct a high-efficiency chiller type refrigeration system.
Furthermore, if the cold heat generating means (40) generates ice, this makes it possible to construct a high-efficiency ice machine.
Further, if the evaporation cooler (43) evaporates water through the moisture permeable membrane (4f), this makes it possible to prevent scale from flowing into the pressure increasing means (50).
Furthermore, if outside air that is introduced into the moisture discharging means (60) is dehumidified in the humidity controlling means (73), this makes it possible to reduce the water vapor pressure of the outside air, and the input of the pressure increasing means (50) can be reduced to a further extent. As a result, it becomes possible to further improve efficiency.
Further, if various types of waste heats can be utilized in the heat exchanger (7b) of the humidity controlling means (73), this makes it possible to make effective utilization of energy.